Culture

Easily grown in average, medium moisture, well-drained soil in full sun to part shade. Prefers moist loams, but tolerates a wide range of soils. Best with consistent and even moisture. Prune as needed immediately after flowering.

Noteworthy Characteristics

Viburnum plicatum, commonly called Japanese snowball bush, is a dense, upright, multi-stemmed, deciduous shrub which produces snowball-like spherical inflorescences of sterile white flowers along its branches in spring. This species is sterile.

Forma tomentosum, commonly called doublefile viburnum, is the fertile form that was discovered later in time than the sterile species. It is a dense, multi-stemmed, deciduous shrub with distinctively tiered horizontal branching. It typically matures over time in a broad-rounded form to 8-10’ tall with a slightly larger spread. It is native to forests and thickets in China and Japan. Flowers bloom in late April-May in flat-topped, lacecap-like clusters (each to 2-4” but less frequently to 6” wide) which extend along the branches and above the foliage in double rows, hence the common name of doublefile viburnum. Each cluster has an outer ring of large, showy, snow-white, sterile florets (each to 1-2” across) surrounding a central mass of tiny non-showy fertile florets which when fertilized give way to egg-shaped 1/3” long fruits (red maturing to black) and viable seed. Ovate, toothed, strongly-veined, dark green leaves (to 4" long) turn burgundy red to purplish red in fall. A large number of cultivars have been introduced into commerce.

Forma name comes from the Latin tomentosum meaning woolly in reference to fine hairs on young stems and leaf undersides.

‘Summer Snowflake’ is an upright cultivar that matures to 5-8’ tall (infrequently taller). Leaves, flowers and fruits are typically smaller than those found on typical f. tomentosum plants. White lacecap-like flowers bloom in spring (late April-May), but continue to bloom sporadically through summer (hence the cultivar name) and sometimes into early fall. Fruits, a few flowers and autumn foliage color may all be simultaneously present on shrubs in early fall. Introduced by the Canadian Ornamental Plant Foundation.